Is sexual selection the answer to the origin of species?

Timothy Denton writes from Canada:

The discussion in relation to the article, “Liberals will have to accept IQ differences just as Christians have had to accept Darwin,” centred exclusively on the notion of random processes of natural selection. I see this mistake committed so often by both sides of the Darwinian discussion, and it is so elementary. Darwin advanced not one, but two, theories of evolution. Almost everyone talks as if the second book had never been written.

The first, The Origin of Species, published in 1859, states that species speciate: that geographically or otherwise isolated portions of a species gradually mutate under the influence of natural selection into creatures better adapted to some local environment. At some point interbreeding with the species from which they derived becomes genetically or otherwise impossible, and they have become a new species. This process, says Darwin, is the accumulation of innumerable small changes under the influence of natural selection: predators, parasites, and food opportunities, and pressured by the tendency of all species to propagate themselves up to the limits of the carrying capacity of their ecosystem.

Darwin’s second theory, the Descent of Man, or Selection in relation to Sex, published thirteen years after the Origin of Species, in 1871, elaborated a wholly different theory of evolution: one that was purposeful, directed, and non-random—sexual selection. That means us, folks. Men have been selecting women, and women men, for the last hundreds of thousands of years, and through sexual selection man has changed from the furry faced creature he was 100,000 years ago into the big brained, relatively more intelligent creature that he is now. If women had selected men for antlers, we might sport them today. The way we measure the direction of this sexual selection is in the differences between us and our nearest relatives, the chimpanzees and bonobos. All of this is discussed in Geoffrey Miller’s excellent introduction to this topic, The Mating Mind.

Sexual selection is not random. Just think about the person by whom you have had your children, if you have been that lucky. I wish that some element of the sexual selection issue would enter the thinking of those who argue endlessly for and against natural selection. Except for diseases, it is quite possible that the only relevant predator we have faced in the last 30,000 years is ourselves. The real force acting upon us is sexual selection, which is directed, persistent, and increasingly, intelligent.

LA replies:

What you say is important, and I confess to my embarrassment that I’ve never read the Descent of Man. But granted what you’re saying about non-random, sexual selection, this would only apply to changes that have occurred within human evolution, right? In which case this non-random, sexual selection does not explain the origin of species, but only micro changes within the human species. So sexual selection is not an alternative to the theory of natural selection, but a complement to it in the case of man. Would that be a correct statement?

Timothy Denton replies:

The generally accepted view among those who write about evolution is that the separation of proto-mankind from proto-chimpanzee and proto-bonobos some 5-7 million years ago (these are factoids, I would have to look up the dates :-) ) (I hope your irony detector is working!) could easily have been due to the same processes of isolation and sexual selection. Isolate a group for a few tens of thousands of years and they may not wish to breed with one another, for any number of reasons—competition for food, they smell bad, they talk funny, they look different etc.

So sexual selection can drive speciation. Indeed, in the case of the separation of the one species of chimpanzee into human, bonobo and chimpanzee, I think sexual selection played a vital role. Other speciations proved unsuccessful because we wiped them out—such as Neanderthals, or they died for other reasons.

Consequently I have no problem with the view that sexual selection could cause speciation to occur in any formerly single species that chose to breed differently. One the breeding differences are established for long enough, interbreeding may become more difficult until it becomes impossible.

So, respectfully, I suggest that Darwin’s second and ignored theory would also be an independent source of speciation.

Go to some of my utterances on this subject on my personal page, well down the page on “Evolution, Sexual Selection, and Design.”

I strongly urge you to give The Descent of Man a good read. I have read the Origin twice, the Voyage of the Beagle once (excellent on Argentina’s backwardness, the loathing he felt for slave societies, such as Brazil, and on Andean geology), and the Descent once with a good note-taking for the purpose of a university paper last year. Like Adam Smith, another huge unread master, I wish more people who wrote about evolution read more Darwin. He is a whole lot more nuanced and subtle, and he essentially repudiated the theory for which he is so famous by superseding it with another, completely different one, within a short time. Darwin realized, I think, that natural selection was wholly unsatisfactory as an explanation of how people like us went from killing bison with spears to chatting on the Internet within ten thousand years. What Darwin lacked was the almost insane courage to say to Victorian society “Hey! I got it mostly right. But this new theory is better!”.

For what it is worth, I believe in God. When I use the word believe, I mean something quite different from knowing. I know that if I drop a pencil from my hand, it will go towards the floor or the centre of gravity. If God chooses to act through messy biological processes involving lust and discernment, it is not for me to repudiate his methods. I could just as well be a deist or atheist on this topic. I consider sexual selection to be a real and living force in all our lives, thank God. :-D

LA replies:

You write: “Darwin realized, I think, that natural selection was wholly unsatisfactory as an explanation of how people like us went from killing bison with spears to chatting on the Internet within ten thousand years.”

This is a spectacular claim and would have to be backed up by some evidence to be plausible.

Second, I find the idea that sexual selection is the cause of the origin of species to be highly improbable, for the same reason that the theory of evolution of new species by natural selection is highly improbable. What are the characteristics that men and women are drawn to when they choose a mate? Things like looks, health, strength, ability to provide for young, and personal compatibility. Let’s say for the sake of argument that female chimpanzees five million years ago chose larger and cleverer male chimps as their mates than smaller and runtier ones (though I’m not sure this is relevant because I’ve read in Nicholas Wade’s book that mating among chimpanzees is promiscuous). The features that the females are choosing are simply qualities that are already present in the chimp population. All chimps have furry bodies, small brains, and a muzzle instead of a human type external nose, and so on. Sexual selection may result in a stronger, taller, smarter chimp population, but these creatures are still going to be chimps. All the sexual selection in the world is not going to get us from chimps to humans. In order for sexual selection to lead to a new species, there would have to be a vast series of mutations leading in the “right” direction, each of which was sexually selected. Thus the problem of the theory of natural selection is also the problem of the theory of sexual selection: random genetic mutations would have to occur which, when selected, would result in a new life form, with a fully upright posture, without fur on the body and face but with continually growing hair on top of the head, with the sexes much more equal in size, with an external nose, with a forehead, with a brain two or three times larger, and on and on and on. But again, before being selected, these changes must first appear. Thus a more primary problem than selection, whether natural or sexual, is the appearance of the mutations that get selected. Sexual selection does not answer that problem any better than natural selection does.

Terry Morris writes:

Timothy Denton writes: “If God chooses to act through messy biological processes involving lust and discernment, it is not for me to repudiate his methods.”

Okay, first of all, couldn’t this kind of assertion also be made with equal force by a literal six day creationist? If God chooses to act through very ordered biological processes to create the universe and all there is therein, including the solar system and the earth; and to crown that achievement, on the sixth literal twenty four hour day, with the creation of rational moral man as a distinct type, it is not for me to repudiate his methods. Isn’t that an equally valid statement? Wouldn’t it be equally valid to say that if God chose highly intelligent highly advanced little green aliens to come to earth and artificially direct humanoids to choose sexual selection, or whatever the mind can concoct, it is not for any of us to question his methods? C’mon!

LA replies:

Brilliant! Mr. Morris has just shattered the Theo-Darwinian Synthesis which says that, after all, since God is all-powerful and can do anything, why couldn’t he devise a plan of evolution that APPEARS TO HUMANS to be occurring by a random mechanism, but is REALLY directed by God? Why couldn’t he violate the laws of logic and purposefully direct a “random” process to lead to dinosaurs, giraffes, and song birds? Well, Mr. Morris replies, if God can do anything, why couldn’t he also create the world in the biblical six days? Why couldn’t he plant Brontosaurus fossils in rock beds that SEEM to be 150 million years old, but in reality are only 6,000 years old? God can do anything, right?

If Young-Earth Creationism is to be dismissed as counterfactual, illogical, and inherently impossible (which I believe is the case), then the same is true of Theistic Darwinianism, as well as of straight Darwinianism.

Terry M. writes:

In your reply to me you expose the same flaw in Theo-Darwinian thinking that exists within Islam, i.e., the same kind of god that acts arbitrarily, or appears to act arbitrarily; a god we cannot understand; a god that can contradict himself and violate his own nature, the laws of logic and so on. This kind of god is as incompatible with Western thought and culture and tradition as is Allah.

LA replies:

That is really an excellent point. It articulates something I felt but didn’t have the words for, when debating with Theo-Darwinians whose bottom line was the insistent all-purpose mantra that God can do anything, God can make two plus two equal five.

O’Brien in Nineteen Eighty-Four can make two plus two equal five. God cannot.

Timothy Denton writes:

I have had the opportunity to read both Geoffrey Miller’s “The Mating Mind” and Nicholas Wade’s “Before the Dawn,” as well as a number of other Darwinian-oriented explorations of human evolution. I also recommend a fine book by another Miller, Kenneth R. Miller, a biologist, called “Finding Darwin’s God.”

Kenneth Miller’s book will not persuade those fixedly and irrevocably opposed to Darwin, and it is quite obviously a hopeless cause to think that mere reading of books will ever persuade anyone of anything regarding such powerful issues. However, I have found Kenneth Miller’s answers to the atheists of the Dawkins school solidly Christian, and his answers to the creationists solidly Darwinian. Other readers of your blog might wish to read it.

On the notion that sexual selection can be the origin of new species, I see no reason to recant, relent or think it “spectacular.” [LA replies: What I said was “spectacular” was not sexual selection, but the claim that Darwin had recanted natural selection.] It only appears so because Darwin’s second theory is widely ignored. A closer acquaintance with Darwin’s second theory, as expressed in the Descent of Man, and elaborated more in Geoffrey Miller’s The Mating Mind, which recapitulates much recent research into the subject, will be persuasive to those open to that possibility. So far as I understand the issue, speciation through sexual selection is merely biological orthodoxy. That it could be though so outré is a measure of how much debate on the subject of Darwin ignores his second major theory.

A lot of reading in this area has had the effect of making me far less concerned whether Darwin is right on all points, as some insist, of wrong on his major ideas. I have developed a respect for him the same way I have a respect for Aristotle. Both have exercised huge influence. Aristotle was wrong about a number of important questions. Darwin is wrong on a number of important issues. See for instance, “Darwinian Fairytales” by the Australian philosopher David Stove, if you want to read a really excellent skewering of Darwin by a secular humanist with a critical eye for weakness in argument. Nevertheless, Darwin is a truly great thinker. You cannot do biology without him.

As to Terry Morris’ comment, in the end I really have no idea what he is driving at. I wish I had made no mention of belief whatever, in the circumstances. I think it more plausible to hold that evolution is occurring and that it works through both natural selection and sexual selection than any other theory of how we got here, including those which posit miraculous interventions of God or like forces. At a minimum I would reiterate that sexual selection is not random, but is directed and purposeful, and that you and I are here because of it. [LA replies: If we’re talking about mutations, then first the mutations must occur before they are selected; no one said that selection is random, it is the changes that are selected that are random according to the theory.] I fully agree that God could not make two plus two equal five. As to the rest, I recommend some good books in the hopes your readers will find them interesting. It is a fascinating topic.

LA replies:

Mr. Denton recommends some good reading, but he fails to reply to my argument against sexual selection. It would have been nice if he could have given us at least one concrete example of how sexual selection leads to the appearance of a new species or life form.

Timothy Denton continues:

I have been reading through some of your postings on your webpage. The one on white liberal guilt is particular apt.

We are just going to have to let our differences over Darwin stay where they are.

Posted by Lawrence Auster at November 20, 2007 05:48 PM | Send